Salt hydrate-bf3-hgx2 polymerization process



SALT HYDRATE-BF -HgX POLYMERIZATION raocnss Harmon M. Knight, La Marque,and Joe T. Kelly, Dickinson, Tern, assignors, by mesne assignments, toStand an! Oil Company, Chicago, lll., a corporation of Indiana 2 Claims.(Cl. 260-63315) This is a division of our copending application SerialNo. 769,598, filed October 27, 1958.

This invention relates to a catalyst adapted for conversions ofhydrocarbons and processes utilizing the catalyst.

An object of the invention is a catalyst of the ferric pyrophosphate BFtype set out in U.S. 2,824,146, which does not require additional BF Afurther object is a solid catalyst containing ferric pyrophosphatehydrate and BP Other objects will become apparent in the course of thedetailed description of the invention.

It has been discovered that an effective catalyst for many hydrocarbonreactions, particularly polymerization, is obtained by interminglingferric pyrophosphate hydrate- BF complex, as hereinafter defined, andmercuric halide, in a hereinafter defined ratio, Where the halide ischloride or bromidel The catalyst composition consists essentially oftwo solid members. One member is a complex having the empirical formulaFe (P O .aH O.bBF where a is at least 1 and b is from 1 to a. Ferricpyrophosphate forms hydrates with water, which hydrates may contain from1 to as many as 18 moles of water of hydration per mole of ferricpyrophosphate. In general, it is preferred that the complex be formedfrom ferric pyrophosphate hydrate containing from 6 to 9 moles of waterof hydration per mole of ferric pyrophosphate. Boron trifluoride must bepresent in the complex; apparently the BE, complexes with the hydratedWater to form a solid material. In order to attain effective catalyticactivity, it is necessary that the complex contain at least 1 mole ofBB, per mole of the hydrate, and preferably the complex should contain 1mole of BF for each mole of water of hydration present. To illustrate,when ferric pyrophosphate.6I-I O is the hydrate, the complex mustcontain at least 1 mole of BF and preferably contains 6 moles of BPthese two complexes may be written as BE, partial pressure drops veryrapidly at first and then gradually approaches a constant value. Itappears that a very rapid reaction between the BF and some of the waterof hydration takes place. This initially rapid reaction is then followedby a relatively slow reaction between the remaining molecules of hydratewater and additional BF In the case of ferric pyrophosphate containing11 moles of hydrate water per mole of the salt, it appears that 4 or5moles of hydrate water are rapidly reacted. However, stirring of finelypowdered hydrate salt in the presence of excess BF at about roomtemperature for a period of about 20 hours, results in the reaction of 12,981,770 Patented Apr. 25, 1961 ice mole of B1 for each mole of hydratewater present in the ferric pyrophosphate hydrate.

The solid complex of ferric pyrophosphate hydrate and BF has moderatecatalytic activity and may be used for purposes such as polymerizingisobutylen-e. This complex has no activity for the difficultethylene-isobutane alkylation reaction or ethylene polymerization. Ithas been found that a catalyst system of very great polymerizationactivity is obtained by intermingling the defined ferric pyrophosphatehydrate-BF, complex with mercuric chloride or mercuric bromide in aweight ratio of ferric pyrophosphate to HgX from about 1 to about 75.The composition consisting essentially of the defined complex and HgX inthis ratio is very effective for promoting the diflicult ethylenepolymerization reaction. The bromide containing catalyst is preferredfor ethylene-isobutane alkylation.

The defined composition of complex and HgX may be used as such; thecomposition may be used in the form of a powder or shaped into pellets.Or, the catalyst composition may be supported on a carrier such asalumina, pumice, silica, silica alumina and carbon.

The catalyst may be used at any temperature below the temperature atwhich the salt hydrate decomposes, that is, loss of all its water ofhydration. The temperature of operation may be as low as -25 C. or evenlower. Temperatures as high as C. and even higher may be used with someof the hydrates which have relatively high decomposition temperatures.For example, ferric pyrophosphatejH o has been heated for 20 hours at168 C. without losing water of hydration. More usually the temperatureof operation will be below about 30 C. Low temperatures favor theformation of the hydrocarbons having 6 to 7 carbon atoms and diisopropylin ethylene-isobutane reaction. It is preferred to operate thisalkylation process at a temperature between about -25 C. and +5 C.

Suflicient pressure is maintained on the system to keep a substantialportion of the hydrocarbons charged in the liquid state. -In general,pressures will be between about 50 and 1060 psi. and preferably betweena'bout'lOO and 600 p.s.i. for alkylation or polymerization.

The reactants in the hydrocarbon charge to the alkylation process areisoparafiin, or aromatic hydrocarbon and olefin. The olefin containsfrom 2 to about 12 carbon atoms. Examples of suitable olefins areethylene, propylene, butene-2, hexene and octene; in addition to these,the olefin polymers obtained from propylene and/or butylene are alsosuitable for use in the process, such as codimer, propylene trimer,propylene tetramer and butylene trimer. It is preferred to operate withethylene or propylene.

The aromatic hydrocarbons must be alkylatable by the particular olefinused. It is self-evident that an aromatic hydrocarbon which containsalkyl substituents positioned so that steric hindrance would prevent orgreatly reduce the possibility of alkylation with the particular olefinshould not be subjected to the process. Examples of particularlysuitable aromatic hydrocarbons are benzene, toluene, xylene,trimethylbenzenes, and the other alkyl analogues, such as propyl andbutyl, the naphthalene aromatic hydrocarbons, such as the mono anddi-substituted methylnaphthalencs.

The isoparafiin reactant is defined as a paraflinic hydrocarbon whichhas a tertiary hydrogen atom, i.e., paraffins which have a hydrocarbonatom attached to a tertiary carbon atom. Examples of these areisobutane, isopentane (Z-methylbutane), Z-methylpentarie,Z-methylhexane, 3- methylhexane, 2,3-dimethylbutane (di-isopropyl) and2,4 dimethylhexane. Thus the isoparafiins usable as one reactant in theprocess contain from 4 to 8 carbon atoms.

Inthe isoparafiin-olefin system, the alkylation reaction entiallypolymerizes ethylene and other olefins.

preferred to operate with an isoparaffin to olefin mole ratio of betweenabout and 15.

The presence of non-reactive hydrocarbons in the hydrocarbon chargeisnot detrimental unless the reactants become excessively diluted. Forexample, the isoparafiin may also contain isomers of the normalconfiguration. The olefins may contain paraffins of the same carbon.number. Mixtures of2 or more isoparaffins or 2 or more aromatichydrocarbons, or 2 or more olefins may be charged. In general, when aparticular product distribution is desired, it is preferable to operatewith a single isoparaffin and a single olefin, for example, technicalgrade isobutane and ethylene, i.e., about 95% purity.

The reactants may be mixed together before they are charged into thereactor. Or, they may be charged into the reactor separately. Or, aportion of the olefin may be blended with the isoparaffin or aromaticbefore introduction into the reactor and the remainder of the olefininjected into the reactor. The charge may be introduced all at one pointinto the reactor or it may be introduced at 2 or more points. Thealkylation reaction is somewhat exothermic and temperature control isfacilitated by introducing the olefin into the reactor at more than onepoint.

The contacting of the isoparafiin or aromatic hydrocarbon and the olefinin the presence of the defined catalyst pair is continued until anappreciable amount of alkylate has been formed. In batch reactions, itis possible to virtually extinguish the olefin, i.e., convertsubstantiallly 100% of the olefin by a sufticientlylong periodofcontacting. When operating in a continuous flow system, it may bedesirable to have a time of contacting such that substantial amounts ofolefin are not converted and obtain the complete conversion of theolefin by a recycle operation. The time of reaction will be determinedby the type of hydrocarbons charged, the ratio of isoparafiin oraromatic to olefin, the degree of mixing in the contacting zone and thecatalyst usage. A few tests will enable one to determine the optimumtime of contacting for the particular system of operating conditionsbeing tried.

The catalyst system is distinguished by its ability to polymerizeethylene. Other olefins such as propylene, butylene, isobutylene, etc.,are polymerized by the catalyst system of the invention. Even in thepresence of isobutane, the system containing mercuric chloride prefer-The catalyst containing mercuric bromide is not as partial to thepolymerization reaction. The polymerization reaction is carried outusing the olefin in substantially the liquid state and otherwise underconditions similar to those described hereinabove for the alkylationreaction.

The hydrocarbon reaction may be carried out in a reactor which may be avessel providing for a batch-type reaction, i.e., one wherein thedesired amount of isoparaffin or aromatic and olefin are charged to aclosed vessel containing the catalyst pair and the vessel thenmaintained at the desired temperature for the desired time. At the endof this time, the hydrocarbon product mixture and unreacted materialsare withdrawn from the vessel and processed to separate the alkylateproduct from the un reacted materials and lower and higher molecularweight materials. The reaction may be carried out in a fixed bedoperation wherein the reactants are flowed through a bed of catalyst,the space velocity being controlled so that the desired amount ofreaction is obtained during the passage of the reactants through thebed. Under some conditions, a moving bed of catalyst may be utilized.

In still another set of circumstances, a fluidized bed may be utilizedwith the incoming stream of reactants providing the energy for thefiuidization of the catalyst. Other methods of operation common in thecatalytic refining aspects of the petroleum industry utilizing solidcatalyst may be readily devised.

Tests For purposes of illustration, the results of comparable testsusing a catalyst composition of the invention and the complex alone areset out below.

The tests were made as follows: g. of

P64 (P 07) 3.9H2O

and 200 ml. of isobutane were charged to a dry 4-liter carbon steelbomb. The bomb was then placed in an ice bath and cooled. BF was slowlyadded with care to avoid overheating of the salt as a result of theexothermic reaction. The bomb was gradually pressured to 250-300p.s.i.g. with BF and allowed to stand until the desired amount of BF hadbeen taken up, after which the bomb was depressured and evacuated. TheHgX (when used) was added and then 1000 g. of a blend of isobutane andethylene were charged (3/ 1 molar 1/0). The bomb was rocked 20 hours at1525 C. and then sampled for Podbielniak distillation analysis.

T est 1.Only 18 weight percent of alkylate were obtained when only theferric pyrophosphate.9H O.9BF complex was present in the reactor. Thiscompares with an alkylate yield of about 30% when BF alone is used as acatalyst in this same system.

Test 2.In this test, mercuric bromide was used in conjunction withferric pyrophosphate.9H O. Sufiicient BF was present in the complex tohave a molar ratio of BF to hydrate water of 0.8. The mercuric bromidewas present the the reactor in an amount such that the ferricpyrophosphate to mercuric bromide weight ratio was 2.2. In this test allthe ethylene reacted. The yield of total alkylate, based on ethylenecharged, was 178 weight percent; the product fractions consisted ofisopentane, 12%, hexanes, 30%, octanes, 56% and nonanes and higher, 76%.The hexanes and octanes had essentially O bromine number; the nonan-eplus fraction had a bromine number of 17.

Test 3.In this test, two runs Were carried out at conditions identicalexcept for the weight ratio of ferric pyrophosphate -to mercuricchloride. Ferric pyrophosphate.9H O and BF were charged to the reactorto obtain a complex containing 0.8 mole of BF per mole of hydrate water.In Run 3a, the weight ratio of ferric pyrophosphate to mercuric chloridewas 2.2. The total yield of product, based on ethylene charged-all ofwhich was reacted, was 143 weight percent. The product consisted ofisopentane, 8%, hexanes, 16%, and higher boiling materials, 119%. Thehigher boiling product had a bromine number of 34.

In Test 3b, the weight ratio of ferric pyrophosphate to mercuricchloride was 18.0. In this test, all of the ethylene charged wasreacted. The yield of product based on ethylene charged was 117 weightpercent, i.e., very little reaction other than polymerization tookplace. The product consisted of isopentane, 7%, hexanes, 13%, and higherboiling materials, 97%. The higher boiling material had a bromine numberof 19.

Test 4.-In this test, ferric pyrophosphate.6H O and BF were complexed toobtain a solid material containing 0.3 mole of BF;, per mole of hydratewater. The weight ratio of ferric pyrophosphate in this test to mercuricchloride was 2.2. The total yield of product was 114 based on ethylenechaIged-all of which was reacted. The product consisted of isopentane,4%, hexanes, 7 and higher boiling materials, 103%. The higher boilingmaterial had a bromine number of 10. Thus having described theinvention, what is claimed is:

1. An ethylene polymerization process comprising concatalyst consistingof (1) a complex having the empirical 5 formula Fe (P O-;) .aH O.bBFwhere a is at least 1 and b is from 1 to a and (2) HgX where X is fromthe class of chloride and bromide where the molar ratio of saidpyrophosphate to said mercuric halide is from about 1:1 to about 75:1.

2. The process of claim 1 where said catalyst consists of (1) thecomplex Fe (P O .9H O.9BF and (2) HgCl where the weight ratio of saidpyrophosphate to said chloride is about 2:l-5:1.

References Cited in the file of this patent UNITED STATES PATENTS ByrneJune 29, 1937 Kelly et a1. Feb. 18, 1958

1. AN ETHYLENE POLYMERIZATION PROCESS COMPRISING CONTACTING ETHYLENE, ATA TEMPERATURE BELOW THE TEMPERATURE OF DECOMPOSITION OF FERRICPYROPHOSPHATE HYDRATE AND AT A PRESSURE SUFFICIENT TO MAINTAIN ASUBSTANTIAL PORTION OF SAID REACTANT IN THE LIQUID STATE, IN THEPRESENCE OF A CATALYST CONSISTING OF (1) A COMPLEX HAVING THE EMPIRICALFORMULA FE4(P2O7)3.AH2O.BBF3 WHERE "A" IS AT LEAST 1 AND "B" IS FROM 1TO "A" AND (2) HGX2 WHERE X IS FROM THE CLASS OF CHLORIDE AND BROMIDEWHERE THE MOLAR RATIO OF SAID PYROPHOSPHATE TO SAID MERCURIC HALIDE ISFROM ABOUT 1:1 TO ABOUT 75:1.